1. Field of the Invention
The present invention relates to a stator for a dynamoelectric machine such as an automotive alternator, for example, and particularly to a stator winding construction for suppressing protrusion of a lead wire of a stator winding from a coil end group.
2. Description of the Related Art
In recent years, compactness, high output, and improved quality have come to be in increasing demand in dynamoelectric machines such as automotive alternators, for example. Concerning compactness and high output in automotive alternators in particular, improvements in space factor of electrical conductors housed inside a magnetic circuit of a stator, and alignment in rows and increases in density of crossover portions of a stator winding (the crossover portions outside a stator core being called coil ends) are required.
A construction has been proposed in International Publication No. WO 92/06527 (Gazette), for example, attempting to improve the space factor of the electrical conductors and to achieve alignment in rows and increases in the density of the coil ends by using short conductor segments for the electrical conductors in the stator.
In this International Publication No. WO 92/06527 (Gazette), pairs of U-shaped conductor segments are inserted from a first end surface end of a stator core into pairs of slots in which the slots are separated by a predetermined number of slots. Then, open end portions of each of the conductor segments projecting outward at a second end surface end of the stator core are bent away from each other, and those open end portions are joined together with open end portions of other conductor segments projecting out of slots separated by a predetermined number of slots.
Thus, at the second end surface end of the stator core, pairs of joint portions joining together open end portions of the conductor segments projecting out of each of the pairs of slots are arranged at a predetermined pitch in a circumferential direction so as to line up in single columns in a radial direction, constituting a second coil end group neatly arranged in rows. At the first end surface end of the stator core, return portions of the pairs of conductor segments inserted into each of the pairs of slots are arranged at a predetermined pitch in a circumferential direction so as to line up in single columns in a radial direction, constituting a first coil end group neatly arranged in rows. In addition, four slot-housed portions of the conductor segments are housed in each of the slots so as to line up in a single column in a slot depth direction.
Thus, the space factor of the electrical conductors housed inside the slots is raised and alignment of the coil ends in rows and increased density in the stator winding is enabled, achieving a compact, high-output stator.
In this conventional stator, the stator winding has three winding phase portions, for example, each constructed by joining together large numbers of conductor segments, first end portions (neutral-point connection lead wires) of the three winding phase portions being joined together, in other words, formed into a Y connection, to constitute a three-phase alternating-current winding, and second end portions of the three winding phase portions forming output-wire lead wires for connection to a rectifier. In a dynamoelectric machine mounted with this stator, each of the output-wire lead wires is connected to the rectifier, alternating-current power generated in the stator being converted into and output as direct current.
In the conventional stator for a dynamoelectric machine, when the output-wire lead wires of the stator winding are constituted by conductors projecting out of radially-outermost positions inside the slots, the output-wire lead wires are more likely to protrude radially outward from the coil end groups of the stator winding. When the output-wire lead wires protrude radially outward from the outermost radial positions of the coil end groups, there are problems such as interference with the housing when the stator is being installed in the dynamoelectric machine, making mounting of the stator to the housing difficult, and the electrically-insulating coating of the conductor segments may also be damaged, making electrical insulation among the three winding phase portions poor. In addition, when installed in the housing, there are problems such as the clearance between the housing and the lead wires being restricted, making electrical insulation between the housing and the stator winding poor.
The present invention aims to solve the above problems and an object of the present invention is to provide a stator for a dynamoelectric machine enabling mounting to a housing and electrical insulation to be improved by suppressing protrusion of output-wire lead wires of winding phase portions radially outward from outermost radial positions of a coil end group.
With the above object in view, a stator for a dynamoelectric machine includes a cylindrical stator core in which a plurality of slots are disposed in a circumferential direction, and a stator winding having a plurality of winding sub-portions each formed by installing a conductor wire so as to be returned outside the slots at end surfaces of the stator core and to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of a predetermined number of slots, return portions of the conductor wires returned outside the slots being arranged regularly in a circumferential direction to constitute coil end groups. The stator winding includes at least one three-phase alternating-current winding constructed by Y-connecting three winding phase portions composed of the plurality of winding sub-portions. Neutral-point connection lead wires of the three winding phase portions are each led out of a layer other than an outermost layer inside the slots, and one of output-wire lead wires of each of the three winding phase portions is led out of the outermost layer inside the slots. The output-wire lead wires are positioned further inside than an outermost diameter of the coil end group relative to a radial direction.
Therefore, provided is a stator for a dynamoelectric machine improving mounting of the stator to a housing and also improving electrical insulation among the three winding phase portions by avoiding damage to an electrically-insulating coating on the conductor wires by suppressing interference with the housing when the stator is being installed in the dynamoelectric machine, and in addition, improving electrical insulation between the housing and the stator winding by ensuring clearance between the housing and the output-wire lead wire when installed in the housing.